Rubbers, elastomers, resins, and metals have conventionally been used to position head arms of hard disk drives (HDD), or as buffer components. In recent years, rubbers, and especially fluororubber, have increasingly been used in consideration of designs in which the buffering effect is important, the need to reduce noise, etc.
Although conventional fluororubber is a material with excellent shock absorbing properties and cleanliness, it has problems concerning its non-tack properties. For example, when the conventional fluororubber is used as a stopper of the storage of a hard disk drive (HDD), a malfunction due to the tackiness between the stopper and arm becomes a problem.
Patent Document 1 discloses a method for making a rubber surface non-tack by impregnating the surface of a rubber with a solution of a crosslinking agent and a crosslinking accelerator for fluororubber, and crosslinking the rubber again. This technique, however, poses problems such as environmental damage due to a solvent treatment using an excessive amount of solvent, and when a solvent is used to control the penetration of the solution, the performance of the products may vary, sometimes causing operating failures of HDD.
The present inventors have previously proposed a technique of achieving non-tackiness (Patent Document 2) by conducting research from a new perspective, that is, an approach based on formulations without depending on the subsequent processing. More specifically, Patent Document 2 discloses a technique of making a rubber surface non-tack, wherein, in a fluororubber composition comprising a polyol-crosslinkable fluororubber, a crosslinking accelerator composed of a quarternary phosphonium salt, and a polyol crosslinking agent, the ratio of the crosslinking accelerator, i.e., a quarternary phosphonium salt, to the crosslinking agent (crosslinking accelerator/crosslinking agent) blended in the polyol-crosslinkable fluororubber composition is adjusted to at least 0.9 and not more than 5, so as to increase the ratio of the added crosslinking accelerator as compared with conventional fluororubber compositions.
Patent Document 1: JP,04-037094,B
Patent Document 2: WO 2004/094479